Intermediate filaments are protein fibers that absorb tension and support cellular shape; they are often crucial in holding together tissues.
Intermediate filaments are part of the cytoskeleton found in certain animal cells (not in all eukaryotes like microtubules and microfilaments). They are composed of a family of related proteins sharing common structural and sequence features. One protein that forms intermediate filaments is keratin, a fibrous protein found in hair, nails, and skin. They have varying sizes that range between 8-12 nm. As their sizes are in between the microfilaments and microtubules, they take the name “intermediate”.
They also do not form and dissemble quickly. Hence they play no role in movement or transport. They form a network of fibers that maintains the cell shape and makes a cage where nucleus sits. You may think of them as playing the same role as springs in a mattress!
intermediate filaments: protein fibers that contribute to cellular structural elements and are often crucial in holding together tissues.
cytoskeleton: network of protein fibers that help with cellular movement and maintaining its structure/shape.
microtubule: hollow, protein-based tubes that exist in eukaryotic cells and help cells move material around itself and resist compression.
microfilaments: thin protein fibers made up of actin proteins; their fundamental role is to absorb tension.